The present invention relates to a large screen color image display apparatus having a large display area, for instance more than 30 m.sup.2, the display surface of which is constructed by arranging a number of light emitting elements each of which emits light in one of three primary colors, red, green and blue (hereinafter "R", "G" and "B", respectively). More particularly, the invention relates to an arrangement of light emitting elements in which the resolution, color mixing, and brightness of the display surface are significantly improved.
Heretofore, in constructing a color image display apparatus, a large number of picture elements are provided with each picture element being made up of individual light emitting elements each of which emits light in one of three primary colors. Usually each picture element is constituted by arranging three light emitting elements, namely, a red light emitting element, a green light emitting element and a blue light emitting element, in combination.
However, in constructing a large screen color display apparatus using such light emitting elements, the spacing or pitch between the light emitting elements has a lower limit due to inherent structural requirements of the display surface and the light emitting elements themselves. Also, the total number of elements has an upper limit due to economic reasons. Accordingly, the conventional technique is not always satisfactory as to the quality of displayed image. For instance, the primary colors provided by the individual light emitting elements are often observable separately from one another and the brightness of the displayed image is often insufficient.
FIG. 1 shows conventional arrangement of light emitting elements for a display apparatus which produces what is considered the most excellent display quality among the previously known arrangements of light emitting elements. In FIG. 1, reference characters 1R, 1G and 1B designate light emitting elements of three primary colors red (R), green (G) and blue (B), respectively, and 2 the display surface of a large screen color display apparatus which is provided by arranging a number of light emitting elements. The light emitting elements are selected by column and row selecting lines (not shown) and are driven by corresponding video signals.
In FIG. 1, the light emitting elements in each row are arranged at a pitch of P.sub.0 in the order of R, G, B, R, G, . . . , so that the horizontal pitch of light emitting elements of the same color is 3P.sub.0. The same color light emitting elements in odd numbered rows and in even numbered rows as viewed vertically are shifted by P.sub.1 =1.5P.sub.0 from one another. The pitch P'.sub.1 of the rows is usually set to a value which is close to the value P.sub.1. The following description assumes P'.sub.1 =P.sub.1.
It is well known that, in the case where the same color elements in adjacent rows are shifted as shown in FIG. 1, the equivalent sampling pitch of the displayed image in the horizontal direction can be regarded as the shortest element distance of the same color in the horizontal direction. In FIG. 1, the equivalent sampling pitch in the horizontal direction is P.sub.1 =1.5P.sub.0.
Color video signals are sampled and applied to the light emitting elements corresponding to their positions so that they emit light at brightnesses corresponding to the signal amplitudes.
The above-described arrangement of the light emitting elements provides the following results: